Electrical Cable Test Results and Analysis During Fire Exposure (ELECTRA-FIRE), A Consolidation of Three Major Fire-Induced Circuit and Cable Failure Experiments Performed Between 2001 and 2011: Final Report (NUREG-2128)

Abstract

Over the past 10 years, there have been three major test programs exploring realistic electrical
functionality of electrical cables under fire conditions. The three programs were:

The Electric Power Research Institute (EPRI) and the Nuclear Energy Institute (NEI),
2002

Research and test efforts undertaken jointly by EPRI and NEI to investigate,
characterize, and quantify fire-induced circuit failures.

NRC Cable Response to Live Fire (CAROLFIRE), 2008

CAROLFIRE was started at the end of the NEI/EPRI test program. It provides an
experimental basis for resolving five of the six items identified as "Bin 2" circuit
configurations in Regulatory Issue Summary (RIS) 2004-003, "Risk-Informed
Approach for Post-Fire Safe-Shutdown Circuit Inspections."

Improved fire modeling tools for the prediction of cable damage under fire
conditions.

Corresponding EPRI and U.S. Nuclear Regulatory Commission (NRC) technical reports
document the test results; however, only the EPRI tests provided an evaluation of various
parameters affecting the likelihood of cable failure modes. However, these evaluations were
based on a limited set of test data (18 tests). Since then, NRC-sponsored testing has added
several hundred data points on the electrical failure characteristics of electrical cable exposure
to intense thermal conditions. Evaluating these and other parameters using all available test
data would improve understanding of the effects of various parameters on cable failure modes.

During an electrical expert Phenomena Identification and Ranking Table (PIRT) meeting in
2011, it became apparent that having individual experts independently analyze the three data
sets to derive conclusions to support the PIRT was inefficient and impractical. Thus, the NRC,
with support from EPRI and Sandia National Laboratories (SNL), began a project to analyze and
catalogue the whole experimental data set to allow the PIRT panel members to make
responsible technical decisions. This report documents the background work that was done to
analyze the data sets and provides the results in tabular and graphical formats. The authors did
not attempt to remove outliers or perform other probabilistic methods to arrive at the conclusions
in this report. The objective of this report is to present the data in a factual and coherent format
to allow the PIRT panel members to make their best informed decisions.